The conventional fuel injection valve to which the present invention concerns comprises a valve seat, a valve member aligned with the valve seat and capable of engaging and separating therefrom, and an actuator for actuating the valve member. The valve seat includes a valve seat surface defining a conical flow path having a conical surface that has a diameter decreasing in the direction of flow of the fuel, and an injection port having a cylindrical surface communicating with the conical flow path at its downstream side. The valve member has a substantially conical tip and capable of contacting to and separating from the valve seat surface to control the supply of fuel to the injection port. The injection port is slanted with respect to the central axis of the conical flow path in order to efficiently utilize the energy of the swirling fuel due to a swirler in atomizing the fuel. (See Japanese Patent Laid-Open No. 10-184496, for example)
However, in the fuel injection valve that has a fuel injection port slanted with respect to the valve central axis as above described, the angle defined between the conical surface and the cylindrical surface is small to exhibit an acute angle on a side close to the slanted surface and is large at the other side. Therefore, the fuel that flows along the conical surface looses its flow speed at the downstream of such the acute angle to generate a stagnation, resulting in a cause of a deposit of carbon contained in the fuel on the fuel flow path wall surface corresponding to the stagnation. The stagnation easily generates when the slant angle of the injection port with respect to the central axis of the fuel injection valve is large.
Accordingly, the object of the present invention is to provide a fuel injection valve in which the amount of carbon deposit is small.